The optical impression of objects or of the surfaces thereof, particularly surfaces on motor vehicles, is greatly determined by the surface properties thereof. Since the human eye is suitable only to a limited extent for the objective determination of surface properties, there is a need for aids and apparatuses for the qualitative and quantitative determination of surface properties.
Surface properties such as, for example, gloss, orange peel, colour, macrostructure or microstructure, image sharpness, haze, surface structure and/or surface topography and the like are determined.
The prior art discloses apparatuses in which a radiation device emits radiation onto the surface to be analyzed and the radiation reflected and/or scattered by this surface is received by a detector and evaluated. These apparatuses operate satisfactorily and allow objective classification of the surface in question.
However, during the measurement the problem arises that the tilt of the apparatus with respect to the surface for example as a result of curvatures of the surface is not constant, but varies. Especially changes of tilt with respect to the surface in the direction of movement may have dramatical impact on the result of measurement. So even changes of angles by a fraction of degree can seriously falsify the measurement.
It is therefore the object of the present invention to provide an apparatus and a method taking into consideration influences which arise from changes of tilt of the apparatus with respect to the surface. Beside, an apparatus should be provided allowing for a differentiation of such effects which evoke form a change inclination and such effects that are, on the other hand, due to changes in surface condition. Finally, statements shall be enabled regarding the physical causes of changes of radiation reaching the detector devices.